Woods said the fog isn't expected to lift until late morning or early afternoon and may return this evening.

Meanwhile, the number of ships waiting to get into the Port of Houston has grown to 54 from 51 earlier today, while the number waiting to leave is up to 13 from seven shortly before dawn.

In Galveston, five inbound ships are waiting, with two lined up to leave, Woods said.

Zack Edwards, a controller with the Coast Guard in Houston, said foggy conditions make it too dangerous for harbor pilots to guide the huge ocean-going vessels into and out of the port.

"Because of the fog conditions and visibility near zero, we deemed it not safe for the Port of Houston pilots and Galveston pilots to safely navigate vessels through the channel," Edwards said this morning.

In Port Arthur early this morning, 12 ships were lined up to get in and six were waiting to get out, Edwards said. No update was available later on the Port Arthur backlog.